I had a UIPageViewController in scrolling-mode that would allow to pan between view-controllers using a finger gesture. However, I wanted to restrict the panning area to a certain area of the screen, for example as shown in this screenshot:

I do it by subclassing the UIPageViewController, finding its UIScrollView, and adding a new UIPanGestureRecognizer to that scrollView.

I set my subclassed UIPageViewController to be the delegate of that new UIPanGestureRegognizer. I then implement two delegate methods:

In the last override I decide if I want to “eat the event” (reply YES) or if I want the original UIPanGestureViewRecognizer of the UIScrollView to handle it (reply NO). So, the YES-reply means the UIPageViewController will not scroll to the next ViewController.

Here are two code snippets for rotating and resizing UIImage’s without using UIGraphicsBeginImageContext(), because it is not thread-safe and can lead to weird behavior.

In my case the camera-preview when taking a picture in an app I was writing, turned black from time to time. The problem was that I was rotating and resizing the images using UIGraphicsBeginImageContext().

This kept me busy for a while until I found a super simple way to do it: In this tutorial/code-snippet I’ll show you how to write an image-cropper for your iPhone-app.

What do I mean by image-cropper?

Bascially, it’s about giving your users a simple way to select part of an image using pan and pinch gestures. This can be handy when they upload a profile picture or something similar.

Here’s the end result:

How it’s done:

There is one UIScrollView with a large contentSize. Embedded in the scroll-view is a UIView (baseView). And embedded in the baseView is the UIImageView with the Ferrari-picture.

The yellow boxes in the above image represent the iPhone screen and the cropping area.

Because the contentSize is bigger than the bounds of the screen (= frame of _scrollView), the user can pan to select the desired image. Because minimumZoomScale and maximumZoomScale are set, the user can pinch to zoom. (Although I am not sure why it helps to set the initial zoomScale after all other initialization. If it’s done earlier it won’t scroll until zoomed.)

The actual cropping is done by rendering the contents of the view-controller’s view into an ImageContext and then cutting out the portion that (here: roughly) corresponds to the non-dimmed “window” in the center.

But as I said, it took me a while. For some reason I never thought of taking a screenshot first.. ;)

Also this solution has the limitation of pixel size. If you want to crop an image of for example 10000 times 10000 pixels and get half of it, you would expect a 5000x5000 pixel result. However, because of the screenshot technique, the cropped area will never be bigger than the pixels on the iPhone screen.

I’ve scrapped the website where I offer setting up your email-server. While it was fun to learn and experiment with, and while some have expressed interest in the offer, it’s neither pracitcal nor profitable for me to continue offering it.

Please refer to this post for information how to start with the email topic yourself. It describes a simple way of setting up an emailserver with Ubuntu.

I just ditched Google Analytics. It’s like a reflex to add it into website projects, but I don’t really need it. Nor do I want it. I think Google has enough information about us already. And they freely share with the American government it seems. So yeah, goodbye.

Now I’m using one of these tools. I can execute a shell script on my computer now and seconds later I have all the analytics I need. Good looking, useful and best of all, not shared with Google.

Introduction

There are very good reasons to want your own e-mail server. I’ve tried several setups and found the Courier-mailserver the simplest to work with. Here’s a tutorial on how to set it up.

This should take about 15 - 30 minutes.

Expected end-result

Here’s what you will have in the end:

Own email server where you can configure an unlimited number of email addresses with an unlimited number of domain-names. However, in this setup each address is bound to a user on the Linux system.

SMTP and IMAP with encryption. Even though email may travel unencrypted to it’s destination, the link between your mail client and your mail server should be encrypted.

Requirements

Here’s what you need:

An Ubuntu 13.10 server in the cloud (other Ubuntu version should work). You can get those for 5 euros a month or so. (Because a virtual server is just fine for this task. You don’t need 32 Gigs of RAM and 8 cores..)

A domain-name where you can configure DNS. Specifically: You want to change the MX-record.

Some basic knowledge of Linux.

Step-by-step gudie

Ok, I will explain to you now how to install the Courier mail suite. I know there are several popular other ones, but this just happens to be a guide about Courier.

If you get stuck or have special config needs, then please also refer to the end of the article where I list a few helpful links.

Installation

First, connect to your email-server using SSH. Make sure you can execute commands with sudo. Start with

Advanced-Tab

Configuration - Part 5, DNS

Use your domain registrar’s console (or do it yourself) to set the MX record. In this case you’d just set example.com, because you didn’t configure any subdomains such as mail.example.com.

SSL Warnings

Your Mail-program or OS will probably complain about the certificates not being signed. You can decide if you want to have them signed. It doesn’t make much sense if it’s just for yourself. Mark the certificate as “trusted” or add them to your “trusted certs” collection in your keychain.

If it doesn’t work

Try restarting both the server processas as well as your mail-client. Make sure your system trusts the certificates. Double-check your passwords.

As I was trying to verify this tutorial on a testing server it wouldn’t work at first, but restarting the client and accepting the certs permanently did the trick.

What’s next?

That’s it, congratulations. You have your own email-webserver. Here’s a few ideas on what you could do next:

install spamassassin. It’s not difficult and I’m sure you can google it. Or I can write a short post about it in the future.

install GPGTools so you can encrypt your email end-to-end. (this is for Mac, similar software is available for every major OS though.)

install squirrel-webmail if you need/want a web-frontend. Not my kind of thing but I thought I’d mention it.

use a database to manage users.

write filters for courier to automate things.

install the whole thing on a tiny computer like the Raspberry Pi, use a dynamic-DNS vendor that support updating of MX records, configure your router to forward mail to your Pi, and host the whole thing at home. ;)

When developing an app, it’s sometimes nice to have a different logo for debug builds (play-icon in XCode) and archive builds. Especially when the versions behave differently.

Now, you can configure the different behavior by passing different values in “Preprocessor Macros” (Build Settings of your target in XCode), but here is just a quick tip on how to set different app-icons:

There’s many ways to go about it, including a prefix file, but I’m just setting the name of the icon file in “Preprocessor Definitions” like this:

And then in the plist itself I susbstitute the icon-filename with the variable name set above:

I think this is a fantastic read, perhaps especially for folks from the industry like myself. (Because we tend to get too enthusiastic about the tools we create at times.) But it also serves as a warning for those in the inner/englightened circle of information professionals, as well as for those being left out.

The Raspberry Pi board is a delightful device. I use it at home to play music. I just thought about what it would take to use it for file-storage, specifically, as a backup server.

The problem: One can plug in a harddisk and copy some files. But unless the harddisk is in a different place, it’s still vulnerable. If thieves come, they might steal your computer AND your backup-disk. If there is a fire, same problem.

Since the NSA has somewhat killed cloud-computing (or would you stil use Dropbox, etc.?), there’s a need for a new strategy.

Here’s the idea: The Buddy CloudTM.

In my protoype the following things are needed:

Raspberry Pi

USB-Disk

A buddy with the same equipment

Of course the equipment can vary, but the idea is simple: You keep his backups, he keeps yours. Encrypted, so he can’t read your data and you can’t read his.

(The device should always be plugged in so something low-power like the Pi seems useful.)

The syncing can be as simple as FTP, but it can get more sophisticated with rsync and more advanced algorithms.

What do you think? Buddies helping each other out by providing offsite-backups to each other.